The field of art to which this invention relates includes the manufacture of electric storage batteries, and more specifically the making of expanded lead strip for use in the fabrication of positive and negative plates for secondary batteries.
The use of a continuous expanded lead strip in the fabrication of plates for lead-acid batteries is gaining in popularity and is replacing the use of separate cast lead grids. A complete system for fabricating battery plates and which utilizes a continuous expanded lead strip is disclosed in U.S. Pat. Nos. 3,853,626; 3,867,200 and 3,890,160.
One of the problems that is encountered when using expanded lead strip is obtaining expanded lead strip which is substantially flat. A further problem is that in the course of flattening the expanded lead strip there is a tendency for the individual cells of the mesh portions thereof to become distorted and non-uniform.
Therefore, it is a principal object of our invention to make expanded lead strip which has uniform and undistorted cells forming the mesh portions and which is substantially flat.
It often is desirable to reduce the thickness of the mesh portions of the expanded strip, but such reduction tends to cause the expanded strip to become wavy which is undesirable.
Thus, a further object of our invention is to reduce the thickness of the mesh portions without inducing any waviness into the expanded strip.
While lead strip will be referred to throughout, it should be understood that lead alloys, such as lead-antimony and lead-calcium-tin, are included as well as any other metallic strips which are suitable for expanding.